Credit

Caption

Coloured scanning electron micrograph (SEM) of Orb weaver spider (Tetragnatha sp.) spinneret piriform gland spigots with silk beginning to be extruded from the spigot tips. Spinnerets are organs located on the abdomens of spiders from which spider web silk is extruded. The individual spinnerets move independently yet in a highly coordinated manner to build cocoons or webs. Each spinneret is dotted with many tiny spigots, through which various types and thicknesses of silk are extruded. The strong muscles that move the spinnerets also force liquid silk through the narrow spigots. This pressure, as well as external pulling by the spider, rearranges the liquid silk molecules into a solid but flexible thread. Although spider web silk is only about one millionth of an inch thick, it is considered a natural high-performance polymer. The strength of some silk exceeds that of steel, and its toughness exceeds that of kevlar. Magnification: x600 when shortest.